Well, come to think of it, in the CAD program it's easy to get dimensions of something, and at that scale the width of a pencil line in a pencil drawing could be a quarter of an inch or so; perhaps he was concerned the drawing wouldn't be accurate enough.

Though the lines in the CAD program are contributing a bit of thickness on their own so I think the dimensions of various things might be off a bit.

I could check in McKay's for a copy--it's just that Knoxville is an hour's drive away and the books in McKay's are not particularly well organized. It turns out a number of my local libraries (well, local enough to do ILL) have it, so maybe my library can get it reasonably quickly.